Method for depositing a silicon nitride film and film deposition apparatus

ABSTRACT

A method for depositing a silicon nitride film is provided to fill a recessed pattern formed in a surface of a substrate with a silicon nitride film. In the method, a first silicon nitride film is deposited in the recessed pattern formed in the surface of the substrate. The first silicon nitride film has a V-shaped cross section decreasing its film thickness upward from a bottom portion of the recessed pattern. A second silicon nitride film conformal to a surface shape of the first silicon nitride film is deposited.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is based on Japanese Priority Application No.2017-154742 filed on Aug. 9, 2017, the entire contents of which arehereby incorporated herein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a method for depositing a siliconnitride film and a film deposition apparatus.

2. Description of the Related Art

Conventionally, as disclosed in Japanese Laid-Open Patent ApplicationPublication No. 2017-92098, a method for depositing a silicon nitridefilm in a fine recess is known that repeats a process of adsorbing afilm deposition source gas that contains an element constituted of anitride film to be deposited and chloride, and a process of nitridingthe adsorbed film deposition source gas using nitriding active species.In the nitriding process, NH* active species and N* active species aregenerated as the nitriding active species, and a region on which thefilm deposition source gas adsorbs is changed by controlling aconcentration of the NH* active species and the N* active species in thefine recess.

The method for depositing the nitride film performs an initial filmdeposition stage that forms a conformal nitriding film by performing anitriding process mainly using the NH* active species prior to a filmdeposition process, and then performs a film deposition stage in which aconcentration of the N* active species is continuously decreased from ahigh concentration state of the N* active species and a nitride film isdeposited from a trench bottom in a nitriding process. Thus, a nitridefilm is deposited by bottom-up growth from the trench bottom, and then aconformal film is deposited with the high NH* active species, therebydepositing a nitride film without forming a void or a seam in the finetrench.

However, because the method for depositing the nitride film described inJapanese Laid-Open Patent Application Publication No. 2017-92098 needsto change the concentration of the NH* active species and the N* activespecies in accordance with a stage of the film deposition, supplycontrol of the gas during the film deposition may be difficult.

Moreover, when a filling deposition is performed by the bottom-upgrowth, a film is deposited thickly on a bottom portion, whereas thefilm is thinly deposited on an upper portion of a recess. Thus, when thefilm is modified with plasma, the upper portion of the film issufficiently modified, whereas the bottom portion of the film may beinsufficiently modified, which is liable to decrease the film quality.

Therefore, one embodiment of the present disclosure is intended toprovide a method for depositing a silicon nitride film and filmdeposition apparats that can fill a recessed pattern with a high-qualityfilm.

SUMMARY OF THE INVENTION

The present invention is made in light of the above problems, andprovides a film deposition method and film deposition apparatus that canfill a recess with a nitriding film with high bottom-up properties byusing a simple process and apparatus.

According to an embodiment, there is provided a method for depositing asilicon nitride film to fill a recessed pattern formed in a surface of asubstrate with a silicon nitride film. In the method, a first siliconnitride film is deposited in the recessed pattern formed in the surfaceof the substrate. The first silicon nitride film has a V-shaped crosssection decreasing its film thickness upward from a bottom portion ofthe recessed pattern. A second silicon nitride film conformal to asurface shape of the first silicon nitride film is deposited.

Additional objects and advantages of the embodiments are set forth inpart in the description which follows, and in part will become obviousfrom the description, or may be learned by practice of the invention.The objects and advantages of the invention will be realized andattained by means of the elements and combinations particularly pointedout in the appended claims. It is to be understood that both theforegoing general description and the following detailed description areexemplary and explanatory and are not restrictive of the invention asclaimed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view illustrating a filmdeposition apparatus according to an embodiment of the presentdisclosure;

FIG. 2 is a schematic perspective view illustrating an inner structureof a vacuum chamber of a film deposition apparatus according to anembodiment of the present disclosure;

FIG. 3 is a schematic top view illustrating an inner structure of avacuum chamber of a film deposition apparatus according to an embodimentof the present disclosure;

FIG. 4 is a schematic partial cross-sectional view of a vacuum chamberof a film deposition apparatus according to an embodiment of the presentdisclosure taken along a concentric circle of a turntable;

FIG. 5 is another schematic cross-sectional view of a film depositionapparatus according to an embodiment of the present disclosure;

FIG. 6 is a schematic cross-sectional view of a plasma generatorprovided in a film deposition apparatus according to an embodiment ofthe present disclosure;

FIG. 7 is another schematic cross-sectional view of a plasma generatoraccording to an embodiment of the present disclosure;

FIG. 8 is a schematic top view of a plasma generator according to anembodiment of the present disclosure;

FIG. 9 is a schematic planar view illustrating an example of a filmdeposition method according to an embodiment of the present disclosure;

FIG. 10 is a partial cross-sectional view illustrating a third processregion in a film deposition apparatus according to an embodiment of thepresent disclosure;

FIG. 11 is a planar view illustrating an example of a lower surface of ashowerhead part according to an embodiment of the present disclosure;

FIGS. 12A through 12E illustrate a series of processes of an example ofa method for depositing a silicon nitride film according to anembodiment of the present disclosure;

FIG. 13 is a diagram illustrating an example of a sequence of a methodfor depositing a silicon nitride film according to an embodiment of thepresent disclosure;

FIGS. 14A through 14D are diagrams illustrating a series of processes ofan example of a conformal deposition process of a method for depositinga silicon nitride film according to an embodiment of the presentdisclosure;

FIG. 15 is an example of a sequence of a conformal film depositionprocess of a method for depositing a silicon nitride film according toan embodiment of the present disclosure; and

FIG. 16 is a diagram illustrating an example of filling film depositioncombining bottom-up film deposition and conformal film depositionaccording to an embodiment of a method for depositing a silicon nitridefilm.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present disclosure are described below with referenceto the accompanying drawings.

[Film Deposition Apparatus]

To begin with, a film deposition apparatus according to an embodiment ofthe present disclosure is described below. With reference to FIGS. 1through 3, the film deposition apparatus includes a vacuum chamber 1having a substantially flat circular shape, and a turntable 2 having arotational axis coincident with the center of the vacuum chamber 1. Thevacuum chamber 1 is a process chamber to accommodate a wafer therein andto deposit a film on a surface of the wafer. The vacuum chamber 1includes a chamber body 12 having a cylindrical shape with a bottomsurface, and a ceiling plate 11 placed on the upper surface of thechamber body 12. The ceiling plate 11 is detachably placed on thechamber body 12 via a sealing member 13 (FIG. 1) such as an O-ring in anairtight manner.

The turntable 2 is provided in the vacuum chamber 1. The turntable 2 isattached to a cylindrical shaped core unit 21 at its center portion. Thecore unit 21 is fixed to the upper end of a rotary shaft 22 that extendsin the vertical direction. The rotary shaft 22 is provided to penetratethrough a bottom portion 14 of the vacuum chamber 1, and the lower endof the rotary shaft 22 is attached to a driving unit 23 that rotates therotary shaft 22 (FIG. 1) about a vertical axis. The rotary shaft 22 andthe driving unit 23 are housed in the cylindrical case body 20 whoseupper surface is open. The case body 20 is attached to a lower surfaceof the bottom portion 14 of the vacuum chamber 1 via a flange portionprovided at its upper surface in an airtight manner so that inneratmosphere of the case body 20 is isolated from external atmosphere.

As illustrated in FIGS. 2 and 3, a plurality of (five in the example ofthe drawing) circular concave portions 24 is provided in a top surfaceof the turntable 2 along a rotating direction (circumferentialdirection) to receive the plurality of semiconductor wafers (which willbe simply referred to as “wafers” hereinafter) W, respectively. In FIG.3, only a single wafer W is illustrated in one of the concave portions24 for an explanatory purpose. Each of the concave portions 24 is formedto have a slightly larger (for example, 4 mm larger) diameter than that(for example, 300 mm) of the wafer W, and to have a depth substantiallyequal to the thickness of the wafer W. Thus, when the wafer W is placedin the respective concave portion 24, the surface of the wafer W and thesurface of the turntable 2 (where the wafer W is not placed) becomealmost the same height. Each of the concave portions 24 has three, forexample, through holes formed in the bottom, through which lift pins forsupporting a back surface of the respective wafer W and lifting thewafer W penetrate.

FIGS. 2 and 3 are diagrams for explaining an inner structure of thevacuum chamber 1. The ceiling plate 11 is not illustrated in FIGS. 2 and3 for an explanatory purpose. As illustrated in FIGS. 2 and 3, areaction gas nozzle 31, a reaction gas nozzle 32, a reaction gas nozzle33, and separation gas nozzles 41 and 42, which are made of quartz, forexample, are provided above the turntable 2. In the example illustratedin FIG. 3, the reaction gas nozzle 33, the separation gas nozzle 41, thereaction gas nozzle 31, the separation gas nozzle 42, and the reactiongas nozzle 32 are arranged in this order from a transfer port 15 (whichwill be explained later) in a clockwise direction (the rotationdirection of the turntable 2 as illustrated by an arrow A in FIG. 3)with a space therebetween in a circumferential direction of the vacuumchamber 1. Gas introduction ports 31 a, 32 a, 33 a, 41 a, and 42 a (FIG.3) that are base portions of the nozzles 31, 32, 33, 41, and 42,respectively, are fixed to an outer peripheral wall of the chamber body12 so that these nozzles 31, 32, 33, 41, and 42 are introduced into thevacuum chamber 1 from the outer peripheral wall of the vacuum chamber 1so as to extend in a radial direction and parallel to the surface of theturntable 2.

In this embodiment, as illustrated in FIG. 3, the reaction gas nozzle 31is connected to a supply source 130 (not illustrated in the drawings) ofa source gas via a pipe 110, a flow controller 120 and the like (notillustrated in the drawings). The reaction gas nozzle 32 is connected toa supply source 131 (not illustrated in the drawings) of a nitriding gasvia a pipe 111, a flow controller 121 and the like (not illustrated inthe drawings). The reaction gas nozzle 33 is connected to a supplysource 132 (not illustrated in the drawings) of chlorine (Cl₂) gas via apipe 112, a flow controller 122 and the like (not illustrated in thedrawings). The separation gas nozzles 41 and 42 are connected to supplysources (not illustrated in the drawings) of a separation gas via pipesand flow controller valves and the like, respectively. A noble gas suchas helium (He) or argon (Ar) or inert gas such as nitrogen (N₂) gas canbe used as the separation gas. The present embodiment is described byciting an example of using Ar gas as the separation gas.

Each of the reaction gas nozzles 31, 32 and 33 has a plurality of gasdischarge holes 35 that faces downward to the turntable 2 along thelongitudinal directions of each of the reaction gas nozzles 31, 32 and33 at intervals of 10 mm, for example. A region below the reaction gasnozzle 31 is a first process region P1 in which the source gas adsorbson the wafers W. A region below the reaction gas nozzle 32 is a secondprocess region P2 in which the nitriding gas that nitrides the sourcegas adsorbed on the wafer W is supplied, thereby producing a molecularlayer of a nitride. The molecular layer of the nitride constitutes afilm to be deposited. A region below the reaction gas nozzle 33 is athird process region P3 in which chlorine gas activated by plasma issupplied to the reaction product (nitride film) produced in the secondprocess region P2, thereby forming an adsorption blocking group. Here,because the first process region P1 is a region where the source gas issuppled, the first process region P1 may be referred to as a source gassupply region P1. Similarly, because the second process region P2 is aregion where the nitriding gas that reacts with the source gas andproduces the nitride is supplied, the second process region P2 may bereferred to as a nitriding gas supply region P2. Also, the third processregion P3 is a region where chlorine gas is supplied, the third processregion P3 may be referred to as a chlorine gas supply region P3.

A plasma generator 90 is provided around the third process region, forexample, over or laterally to the third process region P3. A plasmagenerator 80 is also provided over the second process region P2. In FIG.3, the plasma generators 80 and 90 are simply illustrated by a dottedline for an explanatory purpose. The plasma generator 90 is constitutedof a remote plasma generator to generate chlorine radicals. In contrast,a type of the plasma generator 80 is not particularly limited, and forexample, the plasma generator 80 may be constituted of an ICP(Inductively Coupled Plasma) plasma generator. Details of the plasmagenerators 80 and 90 will be described below.

A gas that contains silicon and chlorine is selected as the source gas.For example, when a silicon nitride (SiN) film is deposited, a gas thatcontains silicon and chlorine such as dichlorosilane (DCS, SiH₂Cl₂) isselected. Here, a variety of gases may be used as the source gas as longas the source gas contains silicon and chlorine. For example, inaddition to dichlorosilane, another chlorosilane-based gas such asmonochlorosilane (SiH₃Cl), trichlorosilane (SiHCl₃), hexachlorodisilane(Si₂Cl₆) may be used depending on the intended use. DCS is cited as anexample of such a gas that contains silicon and chlorine.

In general, ammonia (NH₃) containing gas is selected as the nitridinggas. A nitrogen (N₂) containing gas may be selected when the nitridinggas is supplied while being activated by plasma other than ammonia gas.Here, the nitriding gas may contain a carrier gas such as Ar in additionto ammonia.

Chlorine gas supplied from the third reaction gas nozzle 33 serves toform on a surface of a wafer W an adsorption blocking group that blocksthe source gas supplied from the first reaction gas nozzle 31 fromadsorbing on the surface of the wafer W. The film deposition apparatusand the method for depositing the silicon nitride film according to theembodiment forms the adsorption blocking region in a wide area, andcontrols so that the source gas uniformly adsorbs on the surface of thewafer W. Here, the method for depositing the silicon nitride film willbe described in detail below. Moreover, FIGS. 2 and 3 illustrate thehorizontally extending nozzle as the third reaction nozzle 33, but thethird reaction gas nozzle 33 may be formed as a showerhead. In FIGS. 2and 3, an example of forming the third reaction gas nozzle 33 as thehorizontally extending nozzle is described, and an example of formingthe third reaction gas nozzle 33 as a showerhead will be describedbelow.

Referring to FIGS. 2 and 3, the ceiling plate 11 includes two convexportions 4 in the vacuum chamber 1. As will be explained below, theconvex portions 4 are attached to a lower surface of the ceiling plate11 so as to protrude toward the turntable 2 to form separation regions Dwith the corresponding separation gas nozzles 41 and 42. Each of theconvex portions 4 has substantially a fan-like planar shape where theapex is removed in an arc shape. For each of the convex portions 4, theinner arc shaped portion is connected to a protruding portion 5 (whichwill be explained below) and the outer arc shaped portion is formed toextend along an inner peripheral surface of the chamber body 12 of thevacuum chamber 1.

FIG. 4 illustrates a cross-section of the vacuum chamber 1 along aconcentric circle of the turntable 2 from the reaction gas nozzle 31 tothe reaction gas nozzle 32. As illustrated in FIG. 4, the convex portion4 is fixed to the lower surface of the ceiling plate 11. Thus, thevacuum chamber 1 includes a flat low ceiling surface 44 (first ceilingsurface) formed as the lower surface of the convex portion 4, and flathigher ceiling surfaces 45 (second ceiling surfaces) which are higherthan the low ceiling surface 44 and formed on both sides of the lowceiling surface 44 in the circumferential direction. The low ceilingsurface 44 has substantially a fan-like planar shape where the apex isremoved in an arc shape. Furthermore, as illustrated in the drawings,the convex portion 4 includes a groove portion 43 at a center in thecircumferential direction. The groove portion 43 is formed to extend inthe radial direction of the turntable 2. The separation gas nozzle 42 ishoused in the groove portion 43. Although not illustrated in FIG. 4, theseparation gas nozzle 41 is also housed in a groove portion provided inthe other convex portion 4. The reaction gas nozzles 31 and 32 areprovided in spaces below the high ceiling surfaces 45, respectively. Thereaction gas nozzles 31 and 32 are provided in the vicinity of thewafers W apart from the high ceiling surfaces 45, respectively. Here,the reaction gas nozzle 31 is provided in a space 481 below and on theright side of the high ceiling surface 45, and the reaction gas nozzle32 is provided in a space 482 below and on the left side of the highceiling surface 45.

Each of the separation gas nozzles 41 and 42 has a plurality of gasdischarge holes 42 h (see FIG. 4) formed along the longitudinaldirection thereof at a predetermined interval (10 mm, for example).

The low ceiling surface 44 provides a separation space H, which is anarrow space, with respect to the turntable 2. When Ar gas is suppliedfrom the separation gas nozzle 42 to the separation space H, this Ar gasflows toward the space 481 and the space 482 through the separationspace H. On this occasion, because the volume of the separation space His smaller than those of the spaces 481 and 482, the pressure in theseparation space H can be made higher than those in the spaces 481 and482 by Ar gas. It means that the separation space H having the higherpressure is formed between the spaces 481 and 482. Moreover, Ar gasflowing from the separation space H toward the spaces 481 and 482 servesas a counter flow against the source gas from the gas first processregion P1 and the nitriding gas from the second process region P2. Thus,the source gas from the first process region P1 is separated from thenitriding gas from the second process region P2 by the separation spaceH. Therefore, mixing and reacting of the source gas with the nitridinggas are prevented in the vacuum chamber 1.

The height h1 of the low ceiling surface 44 above an upper surface ofthe turntable 2 is preferred to be appropriately determined based on thepressure of the vacuum chamber 1 during the film deposition, therotational speed of the turntable 2, and a supplying amount of theseparation gas (Ar gas) in order to maintain the pressure in theseparation space H higher than those in the spaces 481 and 482.

Referring to FIGS. 1 through 3, the ceiling plate 11 further includesthe protruding portion 5 at its lower surface to surround the outerperiphery of the core unit 21 that supports the turntable 2. Theprotruding portion 5 is continuously formed with the inner portions ofthe convex portions 4 and has a lower surface that is formed at the sameheight as those of the low ceiling surfaces 44, in this embodiment.

FIG. 1 is a cross-sectional view taken along an I-I′ line in FIG. 3, andillustrating an area where the ceiling surface 45 is provided. FIG. 5 isa partial cross-sectional view illustrating an area where the ceilingsurface 44 is provided. As illustrated in FIG. 5, the convex portion 4having a substantially fan-like planar shape includes an outer bendingportion 46 at its outer peripheral end portion (at an outer peripheralend portion side of the vacuum chamber 1) which is bent to have anL-shape to face an outer end surface of the turntable 2. The outerbending portion 46 inhibits a flow of gas between the space 481 and thespace 482 through the space between the turntable 2 and the innerperipheral surface of the chamber body 12. As described above, theconvex portions 4 are provided on the ceiling plate 11 which isdetachably attached to the chamber body 12. Thus, a slight space isprovided between the outer periphery surface of the outer bendingportion 46 and the chamber body 12. The spaces between the innerperiphery surface of the outer bending portion 46 and an outer surfaceof the turntable 2, and the space between the outer periphery surface ofthe outer bending portion 46 and the chamber body 12 are set at the samesize as the height h1 (see FIG. 4) of the low ceiling surface 44 withrespect to the upper surface of the turntable 2, for example.

As illustrated in FIG. 5, the inner peripheral wall of the chamber body12 is provided to extend in a vertical direction to be closer to theouter peripheral surface of the outer bending portion 46 at theseparation region H. However, other than the separation region H, asillustrated in FIG. 1, for example, the inner peripheral wall of thechamber body 12 is recessed outward in a range from a location facingthe outer end surface of the turntable 2 to the upper end of the bottomportion 14. Hereinafter, for an explanatory purpose, the concaveportion, having a substantially rectangular cross-sectional view, isreferred to as an “evacuation region.” Specifically, a part of theevacuation region which is in communication with the first processregion P1 is referred to as a first evacuation region E1, and a part ofthe evacuation region which is in communication with the second andthird process regions P2 and P3 is referred to as a second evacuationregion E2. As illustrated in FIGS. 1 through 3, a first evacuation port610 and a second evacuation port 620 are respectively provided at thebottom portions of the first evacuation region E1 and the secondevacuation region E2. The first evacuation port 610 and the secondevacuation port 620 are connected to vacuum pumps 640, which are vacuumevacuation units, via evacuation pipes 630, respectively, as illustratedin FIG. 1. Moreover, a pressure controller 650 is provided between thevacuum pumps 640 and the evacuation pipes 630 in FIG. 1.

As illustrated in FIGS. 2 and 3, although a separation region H is notprovided between the second process region P2 and the third processregion P3, as illustrated in FIG. 3, a casing that partitions a spaceabove the turntable 2 is provided in a region illustrated as the plasmagenerator 80. Otherwise, when the casing is not provided for the plasmagenerator 80, a casing is provided for the plasma generator 80 a, andthe space between the second process region P2 and the third processregion P3 is partitioned. This point will be described later in detail.

As illustrated in FIGS. 1 and 5, a heater unit 7, which is a heatingdevice, is provided in a space between the bottom portion 14 of thevacuum chamber 1 and the turntable 2, and heats a wafer W on theturntable 2 via the turntable 2 up to a temperature determined by aprocess recipe (e.g., 400° C.). As illustrated in FIG. 5, a ring-shapedcover member 71 is provided below, at and near the periphery of theturntable 2 to prevent a gas from entering an area under the turntable 2by separating an atmosphere from a space above the turntable 2 to theevacuation regions E1 and E2 from an atmosphere in which the heater unit7 is placed. The cover member 71 includes an inner member 71 a providedunder the periphery and outside of the turntable 2 and an outer member71 b provided between the inner member 71 a and the inner side wall ofthe vacuum chamber 1. The outer member 71 b is provided to face theouter bending portion 46, which is formed at an outer edge portion atlower side of each of the convex portions 4. The inner member 71 a isprovided to surround the entirety of the heater unit 7 below the outerend portion (and at a slightly outer side of the outer edge portion) ofthe turntable 2.

The bottom portion 14 of the vacuum chamber 1 closer to the rotationcenter than the space where the heater unit 7 is provided protrudesupward to be close to the core unit 21 to form a projecting portion 12a. A narrow space is provided between the projecting portion 12 a andthe core unit 21. Furthermore, a narrow space is provided between aninner peripheral surface of the bottom portion 14 and the rotary shaft22 to be in communication with the case body 20. A purge gas supplyingpipe 72 which supplies Ar gas as the purge gas to the narrow space forpurging is provided in the case body 20. The bottom portion 14 of thevacuum chamber 1 includes a plurality of purge gas supplying pipes 73(only one of the purge gas supplying pipes 73 is illustrated in FIG. 5)which are provided at a predetermined angle interval in thecircumferential direction below the heater unit 7 for purging the spacewhere the heater unit 7 is provided. Moreover, a cover member 7 a isprovided between the heater unit 7 and the turntable 2 to prevent thegas from going into the space where the heater unit 7 is provided. Thecover member 7 a is provided to extend from an inner peripheral wall(upper surface of the inner member 71 a) of the outer member 71 b to anupper end portion of the projecting portion 12 a in the circumferentialdirection. The cover member 7 a may be made of quartz, for example.

The film deposition apparatus 1 further includes a separation gassupplying pipe 51 that is connected to a center portion of the ceilingplate 11 of the vacuum chamber 1 and is provided to supply Ar gas as theseparation gas to a space 52 between the ceiling plate 11 and the coreunit 21. The separation gas supplied to the space 52 flows through anarrow space between the protruding portion 5 and the turntable 2 so asto flow along the top surface of the turntable 2 where the wafers W areto be placed and is discharged toward the outer periphery. The space 50is kept at a pressure higher than those of the space 481 and the space482 by the separation gas. Thus, the mixing of the source gas suppliedto the first process region P1 and the nitriding gas supplied to thesecond process region P2 by flowing through the center area C can beprevented by the space 50. It means that the space 50 (or the centerarea C) can function similarly to the separation space H (or theseparation region D).

In addition, as illustrated in FIGS. 2 and 3, a transfer port 15 isformed in a side wall of the vacuum chamber 1 for allowing the wafers W,which are substrates, to pass between an external transfer arm 10 andthe turntable 2. The transfer port 15 is opened and closed by a gatevalve (not illustrated in the drawings). Furthermore, lift pins, whichpenetrate through the concave portion 24 to lift up the wafer W from abackside surface, and a lifting mechanism for the lift pins (both arenot illustrated in the drawings) are provided at a location where thewafer W is transferred and below the turntable 2 because the wafer W istransferred between the external transfer arm 10 and the concave portion24 of the turntable 2, which is a substrate receiving area, at alocation facing the transfer port 15.

Next, the plasma generator 80 is described below with reference to FIGS.6 through 8. FIG. 6 is a schematic cross-sectional view of the plasmagenerator 80 taken along the radial direction of the turntable 2. FIG. 7is a schematic cross-sectional view of the plasma generator 80 takenalong a direction perpendicular to the radial direction of the turntable2. FIG. 8 is a schematic top view illustrating the plasma generator 80.For an explanatory purpose, parts of the components are simplified ornot illustrated in the drawings.

Referring to FIG. 6, the plasma generator 80 is made of a material thattransmits radio frequency waves, and has a concave portion in its uppersurface. The plasma generator 80 further includes a frame member 81 thatis embedded in an opening 11 a provided in the ceiling plate 11, aFaraday shield plate 82 housed in the concave portion of the framemember 81 and having substantially a box shape whose top is opened, aninsulating plate 83 placed on a bottom surface of the Faraday shieldplate 82, and a coil antenna 85 supported by the insulating plate 83thereon. The antenna 85 has substantially an octagonal planar shape.

The opening 11 a of the ceiling plate 11 is formed to have a pluralityof step portions, and one of the step portions has a groove portion toextend along the perimeter where a sealing member 81 a such as an O-ringor the like is embedded. The frame member 81 is formed to have aplurality of step portions that correspond to the step portions of theopening 11 a, and when the frame member 81 is engaged in the opening 11a, a back side surface of one of the step portions contacts the sealingmember 81 a embedded in the opening 11 a so that the ceiling plate 11and the frame member 81 are kept in an air-tight manner. Moreover, asillustrated in FIG. 6, a pushing member 81 c, which extends along theouter periphery of the frame member 81 that is fitted in the opening 11a of the ceiling plate 11, is provided so that the frame member 81 ispushed downward with respect to the ceiling plate 11. Thus, the ceilingplate 11 and the frame member 81 are further kept in an air-tightmanner.

The lower surface of the frame member 81 is positioned to face theturntable 2 in the vacuum chamber 1 and a projection portion 81 b thatprojects downward (toward the turntable 2) is provided at the perimeterat the lower surface. The lower surface of the projection portion 81 bis close to the surface of the turntable 2 and a space (hereinafterreferred to as the third process region P3) is surrounded by theprojection portion 81 b, the surface of the turntable 2 and the lowersurface of the frame member 81 above the turntable 2. The space betweenthe lower surface of the projection portion 81 b and the surface of theturntable 2 may be the same as the height h1 between the ceiling surface44 and the upper surface of the turntable 2 in the separation space H(FIG. 4).

In addition, the reaction gas nozzle 32 that penetrates through theprojection portion 81 b is provided in the second process region P2. Inthis embodiment, as illustrated in FIG. 6, the nitriding gas supplysource 131 filled with nitriding gas is connected to the reaction gasnozzle 32 through the pipe 111 via the flow controller 121. Thenitriding gas may be, for example, a gas that contains ammonia (NH₃).More specifically, the nitriding gas may be a mixed gas of ammonia (NH₃)and argon (Ar). The nitriding gas whose flow rate is controlled by theflow controller 121 is activated by the plasma generator 80 and issupplied to the second process region P2 at a predetermined flow rate.Here, when the mixed gas of ammonia and argon is used as the nitridinggas, ammonia and argon may be separately supplied, but FIG. 6illustrates an example of supplying ammonia and argon to the reactiongas nozzle 32 in a state of mixed gas for convenience of explanation.

The reaction gas nozzle 32 has a plurality of gas discharge holes 35formed along the longitudinal direction thereof at a predeterminedinterval (10 mm, for example), and the above-mentioned chlorine gas isdischarged from the gas discharge holes 35. As illustrated in FIG. 7,the gas discharge holes 35 are provided to be inclined from a verticaldirection with respect to the turntable 2 toward the upstream rotationaldirection of the turntable 2. Due to this, the gas supplied from thereaction gas nozzle 33 is discharged in a direction opposite to therotational direction of the turntable 2, specifically, toward a gapbetween a lower surface of the projection portion 81 b and the surfaceof the turntable 2. Thus, the flows of the reaction gas and theseparation gas from a space below the ceiling surface 45 that isupstream of the plasma generator 80 toward the second process region P2along the rotation direction of the turntable 2 can be prevented.Furthermore, as described above, because the projection portion 81 bthat is formed along an outer periphery of the lower surface of theframe member 81 is close to the surface of the turntable 2, the pressurein the third process region can be kept high by the gas from thereaction gas nozzle 32. This also prevents the reaction gas and theseparation gas from flowing into the second process region P2.

Thus, the frame member 81 plays a role in separating the second processregion P2 from the surroundings. Hence, the film deposition apparatusaccording to the embodiment includes the frame member 81 together withthe plasma generator 80 to separate the second process region P2.

The Faraday shield plate 82 is made of a conductive material such as ametal and is grounded, although not illustrated in the drawings. Asclearly illustrated in FIG. 8, the Faraday shield plate 82 has aplurality of slits 82 s at its bottom portion. Each of the slits 82 sextends substantially perpendicularly to a corresponding side of theantenna 85 that has the substantially octagonal planar shape.

As illustrated in FIGS. 7 and 8, the Faraday shield plate 82 includestwo support portions 82 a that are provided at upper end portions tobend outward. The support portions 82 a are supported by the uppersurface of the frame member 81 so that the Faraday shield plate 82 issupported at a predetermined position in the frame member 81.

The insulating plate 83 is made of fused quartz, for example, has a sizeslightly smaller than that of the bottom surface of the Faraday shieldplate 82, and is mounted on the bottom surface of the Faraday shieldplate 82. The insulating plate 83 insulates the Faraday shield plate 82from the antenna 85 while passing the radio frequency waves radiatedfrom the antenna 85 downward.

The antenna 85 is formed by winding a pipe made of copper three times,for example, in a substantially octagonal planar shape. Thus, coolingwater can be circulated in the pipe, and the antenna 85 is preventedfrom being heated to a high temperature by the radio frequency wavessupplied to the antenna 85. As illustrated in FIG. 6, the antenna 85includes a standing portion 85 a to which a support portion 85 b isattached. The antenna 85 is maintained at a predetermined position inthe Faraday shield plate 82 by the support portion 85 b. The radiofrequency power source 87 is connected to the support portion 85 b viathe matching box 86. The radio frequency power source 87 is capable ofgenerating radio frequency power having a frequency of 13.56 MHz, forexample.

According to the plasma generator 80 thus structured, when the radiofrequency power source 87 supplies the radio frequency power to theantenna 85 via the matching box 86, the antenna 85 generates anelectromagnetic field. In the electromagnetic field, the Faraday shieldplate 82 cuts the electric field component so as not to transmit theelectric field component downward. On the other hand, the magnetic fieldcomponent is transmitted into the second process region P2 through theplurality of slits 82 s of the Faraday shield plate 82. The magneticfield component activates the nitriding gas supplied to the secondprocess region P2 from the reaction gas nozzle 32 at a predeterminedflow rate.

Next, the plasma generator 90 of the film deposition apparatus accordingto the embodiment of the present disclosure is described below.

FIG. 9 is a planar view of the film deposition apparatus on which theplasma generators 80 and 90 are mounted according to the embodiment ofthe present disclosure. The plasma generator 90 is formed as a remoteplasma generator.

The inductively coupled plasma (ICP) generator 80 using the antenna 85,which is described with reference to FIGS. 6 through 8, is effective togenerate plasma with high intensity and works well when both ionizednitrogen gas and radicalized nitrogen gas may be generated. However,when chlorine ions are not needed and only chlorine radicals are needed,the remote plasma generator is more preferred to the inductively coupledplasma generator. In other words, because the remote plasma generatoractivates chlorine outside the vacuum chamber 1 by plasma, the ionizedchlorine that has a short lifetime is inactivated before reaching thevacuum chamber 1 or the wafer W, and only the radicalized chlorine thathas a long lifetime is supplied to the wafer W. Thus, the activatedchlorine gas dominated by the chlorine radicals that are less activatedthan the ICP plasma generator that directly produces plasma in thevacuum chamber 1 can be supplied to the wafer W. A plasma generatorcapable of supplying the chlorine radicals and hardly supplying theionized chlorine to the wafer W is used for the plasma generator 90according to the embodiment. The remote plasma generator is an exampleof such a plasma generator. However, the plasma generator 90 is notlimited to the remote plasma generator, and a variety of plasmagenerators can be used as long as the plasma generator can mainlygenerate chlorine radicals while hardly generating chlorine ions.

FIG. 10 is a cross-sectional view of a film deposition apparatusincluding a plasma generator 90 according to an embodiment.

As illustrated in FIG. 10, the plasma generator 90 is provided oppositeto the turntable 2 in the third process region P3. The plasma generator90 includes a plasma generation part 91, a gas supply pipe 92, ashowerhead part 93, and a pipe 94. Here, the showerhead part 93 is anexample of a chlorine gas discharge part, and for example, a gas nozzlemay be used instead of the showerhead part 93.

The plasma generation part 91 activates chlorine gas supplied from thegas supply pipe 92 using a plasma source. The plasma source is notparticularly limited as long as it is capable of activating chlorine gasto generate chlorine radicals. For example, an inductively coupledplasma (ICP), a capacitively coupled plasma (CCP), or a surface waveplasma (SWP) may be used as the plasma source.

The gas supply pipe 92 has one end that is connected to the plasmageneration part 91 to supply chlorine gas to the plasma generation part91. The other end of the gas supply pipe 92 is connected to the chlorinegas supply source 132 that stores chlorine gas via an on-off valve and aflow controller 122, for example.

The showerhead part 93 is connected to the plasma generation part 91 viathe pipe 94. The showerhead part 93 supplies chlorine gas that has beenactivated by the plasma generation part 91 into the vacuum chamber 1.The showerhead part 93 has a fan-like shape in a planar view and ispressed downward along the circumferential direction by a press member95 that is formed along the outer edge of the fan-like shape. The pressmember 95 is fixed to the ceiling plate 11 by a bolt or the like (notillustrated), and in this way, the internal atmosphere of the vacuumchamber 1 may be maintained airtight. The distance between a bottomsurface of the showerhead part 93 when it is secured to the ceilingplate 11 and a surface of the turntable 2 may be arranged to be about0.5 mm to about 5 mm, for example.

A plurality of gas discharge holes 93 a are arranged at the showerheadpart 93. In view of the difference in speed on a rotational center sideand an outer peripheral side of the turntable 2, fewer gas dischargeholes 93 a are arranged on the rotational center side of the showerheadpart 93, and more gas discharge holes 93 a are arranged on the outerperipheral side of the showerhead part 93. The total number of the gasdischarge holes 93 a may be several tens to several hundreds, forexample. Also, the diameter of the plurality of gas discharge holes 93 amay be about 0.5 mm to about 3 mm, for example. Activated chlorine gassupplied to the showerhead part 93 is supplied to the space between theturntable 2 and the showerhead part 93 via the gas discharge holes 93 a.

FIG. 11 is a planar view illustrating an example of a lower surface ofthe showerhead part 93. As illustrated in FIG. 11, a downward protrudingsurface 93 c may be provided in a belt-like form along the outercircumference of the lower surface 93 b of the fan-shaped showerheadpart 93. This can uniformly prevent the pressure on the outer peripheralside of the third process region P3 from decreasing in thecircumferential direction. Moreover, the gas discharge holes 93 a may beprovided at the center of the lower surface 93 b of the showerhead part93 in the circumferential direction so as to extend in the radialdirection. Thus, chlorine gas can be supplied in a dispersed manner fromthe central side throughout the outer peripheral side of the turntable2.

Thus, activated chlorine gas may be supplied to the wafer W by using theremote plasma generator 90.

Here, the remote plasma generator is not limited to the structureincluding the showerhead part as illustrated in FIGS. 9 through 11, theremote plasma generator may have the structure using the reaction gasnozzle 33 illustrated in FIGS. 2 and 3. In this case, for example, theplasma generator 91 may be provided on an outer lateral surface of thechamber body 12, and may be configured to supply the chlorine radicalsto the reaction nozzle 33 from the outer lateral surface.

As illustrated in FIG. 1, the film deposition apparatus according to thepresent embodiment further includes a controller 100 that is constitutedof a computer and controls the entirety of the film depositionapparatus. A memory in the controller 100 stores a program by which thefilm deposition apparatus executes the film deposition method (as willbe described below) under a control of the control unit 100. The programis formed to include steps capable of executing the film depositionmethod, and is stored in a medium 102 such as a hard disk, a compactdisc, a magneto-optic disk, a memory card, and a flexible disk. Apredetermined reading device reads the program into a storage part 101,and the program is installed in the controller 100.

Furthermore, the controller 100 also performs control for performing themethod for depositing the silicon nitride film according to theembodiment of the present disclosure, which will be described later.

[Method for Depositing a Silicon Nitride FILM]

Next, a method for depositing a silicon nitride film according to anembodiment of the present invention is described below by citing anexample of using the above-mentioned film deposition apparatus. Themethod for depositing the silicon nitride film includes two differenttypes of deposition process constituted of a bottom-up film depositionprocess to deposit a silicon nitride film having a V-shaped crosssection into a recessed pattern formed in a surface of a substrate, anda conformal film deposition process to deposit a conformal siliconnitride film along a surface shape of the recessed pattern or thedeposited silicon nitride film. Each of the bottom-up film depositionprocess and the conformal film deposition process is described below.

FIGS. 12A through 12E are diagrams illustrating an example of a seriesof processes of the bottom-up film deposition process in the filmdeposition method according to the embodiment of the present disclosure.FIG. 12A is a diagram illustrating an example of a plasma modificationprocess of the method for depositing the silicon nitride film accordingto the present embodiment.

In this embodiment, a silicon wafer is used as the wafer W, and thesilicon wafer has a recessed pattern such as a trench and a via hole. Inthe following embodiment, as illustrated in FIG. 12A, an example ofhaving a trench T formed in a surface of a wafer W is described.Although the trench T is not required to be formed in a surface of thewafer W as long as a certain trench pattern only has to be formed in thesurface of the wafer W to perform filling deposition into the trench andthe via hole, an example of forming the trench T in the surface of thewafer W is described for convenience of explanation. However, the methodfor depositing the silicon nitride film according to the embodiment canbe applied to the wafer W in which a variety of patterns is formedincluding a flat surface.

Moreover, an example of supplying dichlorosilane (DCS, SiH₂Cl₂) andnitrogen gas as a carrier gas from the reaction gas nozzle 31, supplyinga mixed gas of ammonia (NH₃) and argon as a nitriding gas from thereaction gas nozzle 32, and supplying a mixed gas of chlorine and argonas a chlorine-containing gas from the showerhead part 93, is describedbelow. Here, because nitrogen gas that is a carrier gas ofdichlorosilane, and argon gas supplied with the nitriding gas andchlorine gas are both inert gases and do not contribute to the reaction,the inert gases will not be particularly referred to hereinafter.Moreover, the nitriding gas is supplied while being activated (convertedto plasma) by the ICP plasma generated by the plasma generator 80, andthe chlorine-containing gas is supplied while being radicalized by theremote plasma generated by the plasma generator 90. An example of usingnitrogen gas as the separation gas (purge gas) is described below.

First, in the film deposition apparatus described with reference toFIGS. 1 through 11, a gate valve (not illustrated in the drawings) isopened, and the transfer arm 10 (FIG. 3) transfers the wafer W from theoutside to the concave portion 24 of the turntable 2 via the transferport 15 (FIG. 2 and FIG. 3). This transfer is performed by raising andlowering the lift pins (not illustrated in the drawings) via throughholes provided in the bottom surface of the concave portion 24 from thebottom portion side of the vacuum chamber 1 when the concave portion 24stops at a position facing the transfer port 15. By repeating such awafer transfer while intermittently rotating the turntable 2, the wafersW are loaded into the respective concave portions 24.

Then, the gate valve is closed, and the vacuum pump 640 evacuates thevacuum chamber 1 to the attainable degree of vacuum. Then, theseparation gas nozzles 41 and 42 discharge Ar gas as a separation gas ata predetermined flow rate. At this time, the separation gas supplyingpipe 51 and the purge gas supplying pipes 72 and 73 also discharge Argas at a predetermined flow rate, respectively. With this, the pressureregulator 650 (FIG. 1) controls the vacuum chamber 1 to a presetprocessing pressure. Then, the heater unit 7 heats the wafers W to 400°C., for example, while the turntable 2 is rotated in a clockwisedirection at a rotational speed of 10 rpm, for example. The rotationalspeed of the turntable 2 can be set at a variety of rotational speedsdepending on the intended purpose. Also, the plasma generators 80 and 90are turned on.

Subsequently, the reaction gas nozzle 32 (FIG. 2 and FIG. 3) supplies anactivated nitriding gas, and a plasma modification of the surface of thewafer W starts. The surface of the wafer W including the inner surfaceof the trench T is nitride and modified with plasma. The first plasmamodification process performs by rotating the turntable predeterminednumber of times until sufficiently nitriding the surface of the wafer W,finishes when the surface of the wafer W is modified, and stops thesupply of the nitriding gas for a while. The turntable 2 continues torotate while supporting the wafer W.

Here, the plasma modification process of FIG. 12A is not required, andmay be performed as necessary. When the plasma modification process ofFIG. 12A is not performed, FIG. 12B only has to be performed withoutperforming the process illustrated in FIG. 12A after supplying theseparation gas while rotating the turntable 2. Moreover, afterperforming the plasma modification process in FIG. 12A for apredetermined period of time, the process in FIG. 12B is subsequentlyperformed. Before entering the process in FIG. 12B, the showerhead part93 starts supplying chlorine radicals activated by the plasma generator90, and the reaction gas nozzle 31 starts supplying dichlorosilane inaddition to the supply of the nitriding gas from the reaction gas nozzle32.

FIG. 12B is a diagram illustrating an example of a chlorine radicaladsorption process in the bottom-up film deposition process. When theturntable 2 is rotated while supplying dichlorosilane from the reactiongas nozzle 31, an ammonia-containing gas from the second reaction gasnozzle 32, chlorine radicals from the showerhead part 93, and nitrogengas from the separation gas nozzles 41 and 42, the wafer W pass alocation under the third process region P3, thereby supplying chlorineradicals to the surface of the wafer W from the showerhead part 93. Onthis occasion, many chlorine radicals readily reach and adsorb on thetop surface of the wafer W and an upper portion of the trench T, butbecause a lower portion of the trench T is deep, chlorine radicalshardly reach a deep portion around the trench T and hardly adsorb on aportion around the bottom surface of the trench T. In other words, anamount of the adsorbed chlorine radicals decreases toward the bottomsurface and its neighborhood of the trench T from the upper end of thetrench T. FIG. 12B illustrates a state of decrease in chlorine radicalstoward the bottom surface of the trench T, to put it the other wayaround, a state of increase in chlorine radicals toward the top end fromthe bottom.

Here, chlorine reacts with H groups and generates HCl while forming Clradical terminals by being replaced with H groups. Such Cl radicals formadsorption blocking groups for a chlorine-containing gas. As discussedabove, chlorine radicals readily reach the upper portion of the trench,but scarcely reach the deep portion of the trench T, that is, the lowerportion around the bottom portion. Because an aspect ratio of the trenchT is high, many chlorine radicals are replaced by H groups beforereaching the deep portion of the trench T. Hence, while Cl groups thatare adsorption blocking groups densely form on the top surface of thewafer W and the upper portion of the trench T, many H groups of an NH₂structure remain in the lower portion of the trench T and the density ofCl groups decreases.

FIG. 12C is a diagram illustrating an example of a source gas adsorptionprocess in the bottom-up film deposition process. As illustrated in FIG.12C, after the wafer W passes the separation region D and is purged by asupplied purge gas, the wafer W passes the first process region P1,where dichlorosilane is supplied to the wafer W. Dichlorosilane hardlyadsorbs on the region where Cl groups that is the adsorption blockinggroups are present, and adsorbs on a region where the adsorptionblocking groups are absent. Hence, many dichlorosilane molecules adsorbon the bottom surface and its neighborhood, and hardly adsorb on the topsurface of the wafer W and the upper portion of the trench T. In otherwords, dichlorosilane that is the source gas densely adsorb on thebottom portion and its vicinity, and less densely adsorb on the upperportion and the top surface of the wafer W.

FIG. 12D is a diagram illustrating an example of a silicon nitride filmdeposition process in the bottom-up film deposition process. Asillustrated in FIG. 12D, after the wafer W passes the separation regionD and is purged by a suppled purge gas, the wafer W passes the secondprocess region P2, where an ammonia-containing gas activated by plasmais supplied to the wafer W. By supplying the ammonia-containing gas tothe wafer W, dichlorosilane adsorbed in the trench T and suppliedammonia reacts with each other, thereby forming a molecular layer of asilicon nitride film as a reaction product. Here, because manydichlorosilane molecules adsorb on the bottom portion and its vicinity,a silicon nitride film is deposited much around the bottom surface ofthe trench T. Hence, the filling deposition with high bottom-upcharacteristics as illustrated in FIG. 12D can be achieved.

Next, when the wafer W passes the third process region P3, the statereturns to FIG. 12B, and Cl groups that are adsorption blocking groupsadsorb on the upper portion of the trench T and the top surface of thewafer W.

Hereinafter, by rotating the turntable 2 repeatedly while supplying eachreaction gas, a cycle illustrated from FIG. 12B to FIG. 12D arerepeated, a silicon nitride film (SiN film) 110 is deposited from thebottom surface side without closing an opening of the trench T. Then, asillustrated in FIG. 12D, the silicon nitride film 110 with highbottom-up properties that does not close the opening can be depositedwhile forming a V-shaped cross section.

FIG. 12E is a diagram illustrating a silicon nitride film 110 having aV-shaped cross section formed in the trench T. The silicon nitride film110 is thickly deposited on the bottom surface of the trench T, and thesilicon nitride film is more thinly deposited on the upper portion ofthe trench T than on the bottom portion. Thus, by performing thebottom-up film deposition process in the method for depositing thesilicon nitride film according to the embodiment, the silicon nitridefilm having the V-shaped cross section can be deposited in the trench T.

FIG. 13 is a diagram illustrating an example of a sequence of thebottom-up film deposition process illustrated in FIG. 12A through 12E.In FIG. 13, a horizontal axis shows a time axis, and a vertical axisshows types of gases and on/off of plasma. FIG. 13 illustrates asequence from 0 to 5 cycles.

A period of time t0 to t1 illustrates a sequence of the plasmamodification process illustrated in FIG. 12A. In the plasma modificationprocess, the reaction gas nozzle 32 supplies an ammonia (NH₃) containinggas, and the plasma generator 80 is turned on. Hence, during the periodof time t0 to t1, NH₃ plasma is supplied.

A period of time t1 to t6 illustrates a sequence of a first revolutionof the turntable 2. As discussed above, by the rotation of the turntable2, the wafer W placed on the concave portion of the turntable 2 passesthe second process region P2, the third process region P3, theseparation region D, the first process region P1, and the separationregion D in this order.

FIG. 13 illustrates a sequence of timing when each gas is actuallysupplied to a surface of a wafer W. More specifically, in theabove-mentioned film deposition apparatus, the reaction gas nozzles 31and 32, the showerhead part 93, and the separation gas nozzle 41 and 42continuously supply the gases; the wafer W moves by the rotation of theturntable 2; and the gases are supplied to the wafer W at timing whenthe wafer W passes the first to third process regions P1 through P3 andthe separation regions D, respectively, but the sequence in FIG. 13 doesnot illustrate timing when the film deposition apparatus supplies gas,but illustrates timing when the gases are supplied to the surface of thewafer W. Thus, the sequence in FIG. 13 can be applied to not only theturntable type film deposition apparatus but also a film depositionapparatus in which gases are supplied into a process chamber containinga wafer W therein while changing types of the gases sequentially.

During a period from time t1 to t2, a nitriding process is performed.When the wafer W passes the second process region P2, ammonia gassuppled from the second reaction gas nozzle 32 is activated by theplasma generator 80 and is supplied to the surface of the wafer W. Thisis substantially the same as the plasma modification process t0 to t1.By such a nitriding process, NH₂ groups adsorb on the entire surface ofthe wafer W including the inner surface of the trench T, and anadsorption site is formed on the entire surface of the wafer W.

During a period from time t2 to t3, a chlorine radical adsorptionprocess is performed. When the wafer W passes the third process regionP3 by the rotation of the turntable 2, the showerhead part 93 of theplasma generator 90 supplies chlorine radicals to the surface of thewafer W. As described with reference to FIG. 12B, many chlorine radicalsadsorb on the top surface of the wafer W and the upper portion of thetrench T, but hardly adsorb on the lower portion including the bottomsurface of the trench T. Hence, different amounts of chlorine radicalsadsorb on the inner surface of the trench T depending on the depth inthe trench T. The region where chlorine radicals have adsorbed becomesan adsorption blocking region against dichlorosilane containingchlorine, and the region where chlorine radicals do not adsorb remainsas the adsorption site formed in the nitriding process. Here, theadsorption blocking region may be referred to as a non-adsorption site.

During a period from time t3 to t4, a purge process is performed. Whenthe wafer W passes the separation region D by the rotation of theturntable 2, nitrogen gas is supplied to the surface of the wafer W, andthe surface of the wafer W is purged and cleaned.

During a period from time t4 to t5, a source gas adsorption process isperformed. When the wafer W passes the first process region 21 by therotation of the turntable 2, the reaction gas nozzle 31 suppliesdichlorosilane to the surface of the wafer W, and dichlorosilane adsorbson the surface of the wafer W. On this occasion, as described withreference to FIG. 12C, dichlorosilane adsorb on the adsorption sitehaving NH₂ groups much, but do not adsorb on the adsorption blockingregion having adsorbed chlorine very much. Hence, dichlorosilane adsorbson the lower portion of the trench T where the adsorption site isexposed much, but do not adsorb on the upper portion of the trench T andthe top surface of the wafer W very much.

During a period from time t5 to t6, a purge process is performed. Asdescribed in the period from time t3 to t4, when the wafer W passes theseparation region D by the rotation of the turntable 2, nitrogen gas issupplied to the surface of the wafer W, and the surface of the wafer Wis purged and cleaned.

During a period from time t6 to t7, a nitriding process (or nitridingfilm deposition process) is performed. When the wafer passes the secondprocess region P2 by the rotation of the turntable 2, ammonia gassuppled from the reaction gas nozzle 32 is activated by the plasmagenerator 80, then supplied to the surface of the wafer W, and reactswith dichlorosilane adsorbed on the surface of the wafer W, therebydepositing a molecular layer of a silicon nitride film that is areaction product on the surface of the wafer W. As described above,because dichlorosilane adsorbs on the lower portion including the bottomsurface of the trench T, the silicon nitride film is thickly depositedon the lower portion of the trench T. In contrast, the silicon nitridefilm is thinly deposited on the upper portion of the trench T and thetop surface of the wafer W where dichlorosilane has hardly adsorbed.Thus, the silicon nitride film having the V-shaped cross sectiondescribed with reference to FIG. 12E is deposited in the trench T.

In and after the second cycle, cycles similar to the first cycle arerepeated. As illustrated in FIG. 12D, the silicon nitride film havingthe V-shaped cross section is gradually deposited, and the trench T isgradually filled with the silicon nitride film from the bottom surfaceside.

Here, because the silicon nitride film having the V-shaped cross sectionis thick at its bottom part and thin at its upper part, an effect ofplasma modification differs depending on its location. In other words,the thin silicon nitride film formed on the upper portion of the trenchT and the top surface of the wafer W is sufficiently modified by plasma,and is formed as a high-density and high-quality film. However, thesilicon nitride film thickly deposited on the bottom portion of thetrench T is liable to be less densely formed with low quality, withoutbeing modified with plasma. Such a phenomenon seems to occur because thefilm thickness is great while a period of plasma irradiation isconstant, thereby running short of the plasma modification. When theplasma modification is insufficiently performed, a void or a seam isliable to be generated because a film partially collapses in asubsequent process, which may affect the subsequent process and furtherlater processes.

Therefore, in the method for depositing the silicon nitride filmaccording to an embodiment of the present disclosure, after thebottom-up film deposition described with reference to FIGS. 12 and 13 isperformed, a thin and conformal silicon nitride film is deposited and ismodified with plasma well, thereby enhancing quality of the siliconnitride film and preventing the collapse in the subsequent process.

FIGS. 14A through 14D are diagrams illustrating a series of processes ofan example of a conformal film deposition process in the method fordepositing the silicon nitride film according to the embodiment of thepresent disclosure. In FIGS. 14A through 14D, an example of performingthe conformal film deposition process in a state of not depositing asilicon nitride film on a wafer yet, is described because it makeseasier to understand the conformal film deposition process.

FIG. 14A is a diagram illustrating an example of a chlorine radicaladsorption process in the conformal film deposition process, Thechlorine radical adsorption process in the conformal film depositionprocess is performed while stopping the supply of the activatednitriding gas. In this regard, this chlorine adsorption process differsfrom the chlorine adsorption process in the bottom-up film depositionprocess.

In the chlorine radical adsorption process in the conformal filmdeposition process, the turntable 2 is rotated predetermined number oftimes while the showerhead part 93 supplies chlorine radicals, therebyadsorbing chlorine radicals on the surface of the wafer W including theinner surface of the trench T. In the chlorine radical adsorptionprocess, although the separation gas nozzles 41 and 42 supply nitrogengas that is the separation gas, a state of not supplying dichlorosilanethat is the source gas from the reaction gas nozzle 31, and notsupplying ammonia gas that is the nitriding gas from the reaction gasnozzle 32, is maintained.

As described above, the chlorine radicals control the adsorption ofdichlorosilane because the chlorine radicals have an adsorption blockingeffect with respect to dichlorosilane that contains chlorine. In thechlorine radical adsorption process, the chlorine radicals having suchan adsorption blocking effect are caused to adsorb until thinly reachingthe entire surface including the bottom and its surroundings of thetrench T, and forms the adsorption blocking region such thatdichlorosilane conformally adsorbs on the surface of the wafer along theshape of the surface of the wafer W. In other words, the chlorineradicals do not necessarily have to conformally adsorb on the surface ofthe wafer W, the adsorption blocking region is formed so that unevenadsorption of dichlorosilane is prevented and that conformaldichlorosilane adsorbs on the entire surface of the wafer W when thenext dichlorosilane is suppled.

Such an adjustment to an area of the adsorption blocking region isperformed by adjusting a supply period of the chlorine radicals. Withrespect to the film deposition apparatus according to the embodiment, aperiod of the chlorine radical adsorption process can be readilyadjusted by adjusting how many times the turntable 2 is rotated whilecontinuing the radical adsorption process. In other words, by setting anumber of revolutions of the turntable 2 while continuing the chlorineradical adsorption process at a high value, the chlorine radicals adsorbto the neighborhood of the bottom surface and the adsorption blockingregion is formed widely, whereas the adsorption range narrows bydecreasing the number of revolutions of the turntable 2. When theadsorption blocking region is formed in a wide range, dichlorosilane islikely to conformally adsorb, but because the adsorption is blocked, thefilm deposition rate negatively decreases. Hence, the period of time ofthe chlorine adsorption process is preferably adjusted to an appropriateperiod. When the rotational speed of the turntable 2 is 10 rpm, forexample, by continuing the chlorine radical adsorption process during 3to 5 revolutions of the turntable 2, dichlorosilane conformally adsorbson the surface of the wafer W.

FIG. 14B is a diagram illustrating an example of a source gas adsorptionprocess. In the source gas adsorption process, the source gas containingsilicon and chlorine is supplied to the surface of the wafer W. In otherwords, the reaction gas nozzle 31 supplies dichlorosilane. Thus,dichlorosilane that is the source gas adsorbs on the surface of thewafer W. On this occasion, because the adsorption blocking region isformed in a relatively wide range, dichlorosilane that is the source gasthinly and conformally adsorbs on the surface of the wafer W along thesurface shape of the wafer W. In other words, dichlorosilane thinlyadsorbs along the inner surface of the trench T.

FIG. 14C is a diagram illustrating an example of a nitriding process. Inthe nitriding process, ammonia that is the nitriding gas is supplied tothe surface of the wafer on which dichlorosilane has adsorbed. In otherwords, the reaction gas nozzle 32 supplies the nitriding gas, and thenitriding gas activated by the plasma generator 80 is supplied to thesurface of the wafer W. Activated ammonia reacts with dichlorosilane,and a molecular layer of silicon nitride that is a reaction product isdeposited on the surface of the wafer W. Because dichlorosilaneconformally adsorbs on the surface of the wafer W along the surfaceshape of the wafer W, the molecular layer of the silicon nitride film isconformally deposited.

Here, the supply of the source gas from the reaction gas nozzle 31 andthe supply of the nitriding gas from the reaction gas nozzle 32 maystart at the same time. As illustrated in FIGS. 2, 3 and 9, because thewafer W reaches the source gas supply region P1 after passing throughthe chlorine supply region P3, and then reaches the nitriding gas supplyregion P2 when the turntable 2 is rotated in a clockwise fashion, thenitriding process is performed after the source gas adsorption processeven if the supply of the source gas and the nitriding gas starts at thesame time. In other words, here, the same operation as that of thebottom-up film deposited is performed.

Because the nitriding gas activated by plasma is supplied in thenitriding process, the modification of the silicon nitride film isperformed at the same time. Here, because a molecular layer of thedeposited silicon nitride film is thin, the plasma reaches a deepportion of the trench T, thereby performing the plasma modificationuniformly. Hence, a high-quality silicon nitride film that issufficiently modified can be deposited.

Here, during the source gas adsorption process and the nitriding processillustrated in FIGS. 14B and 14C, respectively, the supply of chlorineradicals may be stopped or may not be stopped. In terms of moving to thenext chlorine radical adsorption process smoothly, the supply ofchlorine radicals is not preferably stopped. The chlorine radicaladsorption process illustrated in FIG. 14A is continuously performed fora predetermined period of time while rotating the turntable 2 multipletimes, whereas the source gas adsorption process and the nitridingprocess in FIGS. 14B and 14C are performed while rotating the turntable2 only one time. In other words, in the arrangement illustrated in FIGS.2, 3 and 9, the wafer W on the turntable 2 receives the supply of sourcegas at the first process region P1 after receiving the supply ofchlorine radicals at the third process region P3, and receives thesupply of chlorine radicals by entering the third process region P3immediately after the source gas adsorbed on the surface of the wafer Wis nitrided so that a molecular layer of a SiN film is deposited on thesurface of the wafer W at the second process region P2. Thus, thesequence from FIG. 14A to 14C can be continuously performed withoutstopping the supply of chlorine radicals.

Here, in the source gas adsorption process and the nitriding process ofFIGS. 14B and 14C, by nitriding the source gas, the molecules terminatewith hydrogen radicals of an NH₂ structure, and an adsorption site isformed for the source gas. Subsequently, when chlorine radicals aresupplied in the chlorine radical adsorption process in FIG. 14A, Hgroups of the NH₂ structure is converted to Cl groups. As discussedabove, because the source gas contains chlorine and because chlorineatoms do not adsorb to each other, the source gas does not adsorb on alocation that is terminated with chlorine. Thus, the locationsterminated with Cl groups serve as adsorption blocking groups, and blockthe adsorption of the source gas. Here, many chlorine radicals adsorb onthe surface of the wafer W and an upper portion of the trench T in thefirst revolution because chlorine radicals readily reach the surface ofthe wafer W and the upper portion of the trench T, but the turntable 2has to be rotated more to cause chlorine radicals to reach the deepportion of the trench T because chlorine radicals are unlikely reach alower portion and the bottom portion of the recessed pattern. To achievethis, in the method for depositing the silicon nitride film in theembodiment, a period of time when only chlorine radicals and theseparation gas are supplied is extended longer than a period of timewhen the source gas and the activated nitriding gas are suppled, therebydepositing a thin and conformal silicon nitride film layer to the shapeof the trench T. By depositing such a thin and conformal silicon nitridefilm, the nitriding gas activated by plasma reaches the deep portionnear the bottom surface of the trench T in the nitriding process of FIG.14C, and an effect of the plasma modification can be enhanced due to thethin film thickness, thereby depositing a high-quality silicon nitridefilm.

Thus, consecutively repeating the processes from FIG. 14A to FIG. 14C, aconformal silicon nitride film to the surface shape of the trench T isgradually deposited in the trench T. Although a deposition rate is notas high as ordinary film deposition due to an influence of chlorineradicals that are the adsorption blocking groups, the high-qualitysilicon nitride film on which the plasma modification is sufficientlyperformed can be deposited without closing the opening of the trench T.

When such a high-quality and conformal silicon nitride film 111 that issufficiently modified with plasma is formed on the silicon nitride film110 formed by the bottom-up film deposition having the V-shaped crosssection described with reference to FIGS. 12 and 13, total quality ofthe silicon nitride film 110 and 111 filled into the trench T can beimproved. In other words, by inserting layers of the high-density andhigh-quality conformal film 111 into the less dense bottom-up film 110,a state of filling hard reinforced layers into a silicon nitride film isformed, thereby preventing the partial collapse of the silicon nitridefilm 110 and 111.

Hence, by performing the bottom-up film deposition described withreference to FIGS. 12 and 13 and the conformal film depositionalternately, a high-quality film can be formed while maintainingproductivity. That is, by repeating a two-step film depositionconstituted of the bottom-up film deposition having high productivitywhile having a slight concern about the film quality of the bottomportion, and the conformal film deposition to cover a film formed by thebottom-up film deposition with a conformal film wholly having highquality while having less productivity, the trench T can be filled withthe silicon nitride films 110 and 111 structured by alternately stackingthe bottom up film 110 and the conformal film 111 in layers.

Here, a proportion of performing the bottom-up film deposition and theconformal film deposition can be properly determined depending on theintended purpose. The proportion of the bottom-up film is increased whenthe productivity is prioritized, whereas the proportion of the conformalfilm deposition is increased when the film quality is prioritized.

FIG. 14D is a diagram illustrating an example of the plasma modificationprocess. In the plasma modification process of FIG. 14D, the reactiongas nozzle 32 supplies the nitriding gas activated by the plasmagenerator 80 to the SiN film, thereby modifying the SiN film with theplasma. This process performs the same operation as that of the plasmamodification process performed in FIG. 12A, but differs from the plasmamodification process in FIG. 12A in that modification of the depositedsilicon nitride film is intended. In a final stage of the trenchfilling, when filling the trench T with the silicon nitride film ends,such a plasma modification process may be performed. Otherwise, even notin the final stage, when the conformal film deposition process ends andbefore the process moves to the bottom-up film deposition process, theplasma modification process may be performed.

When the nitridation of the silicon nitride film is insufficient, thesilicon nitride film is sufficiently nitrided by supplying the nitridinggas activated by plasma, and a high-density, fine and high-qualitysilicon nitride film can be deposited. As described above, the plasmamodification process is performed by supplying only the nitriding gasactivated by plasma and the separation gas without supplying the sourcegas and the chlorine radicals. The surface of the wafer including theinner surface of the trench T is nitrided and modified by the plasmamodification process. Here, the plasma modification process only has tobe performed as necessary and is not required similar to the plasmamodification process in FIG. 12A. However, the plasma modificationprocess is preferably performed to obtain a further high-quality siliconnitride film.

After the trench filling film deposition ends by alternately repeatingthe bottom-up film deposition and the conformal film deposition process,the supply of all gases and the plasma generators 80 and 90 are stoppedwhile the rotation of the turntable 2 is stopped. Then, the turntable 2is intermittently rotated and stopped, and the wafers W are lifted bylift pins, and are sequentially carried out of the vacuum chamber in anopposite procedure to the carry-in of the wafers W. The high-qualitysilicon nitride film 110 and 111 having less voids and seams and whosestrength is enhanced by the conformal film deposition is deposited inthe trench T formed in the surface of the wafer W.

Thus, according to the method for depositing the silicon nitride film ofthe embodiment, a recessed pattern can be very efficiently filled with ahigh-quality silicon nitride film by combining bottom-up film depositionthat can fill a trench T without generating a void and a seam with highproductivity and conformal film deposition that can deposit a conformaland high-quality silicon nitride film along a surface shape of a waferor an already deposited film.

FIG. 15 is a diagram illustrating an example of a sequence of theconformal film deposition process of the method for depositing thesilicon nitride film according to an embodiment of the presentdisclosure. In FIG. 15, a horizontal axis shows a time axis, and avertical axis shows types of supplying gases and an on-off of plasma.FIG. 15 illustrates a sequence of 1 to 5 cycles.

A period of time t1 to t6 illustrates a sequence of a first revolutionof the turntable 2. In the first revolution of the turntable 2, chlorineradical adsorption process is performed. In the chlorine radicaladsorption process, the plasma generator 90 supplies chlorine radicals.Hence, in a first cycle, chlorine (Cl₂) plasma is on, and the chlorineradicals are supplied. In addition, nitrogen(N₂) is supplied as a purgegas.

During a period from time 1 to t6, chlorine radicals adsorb on a surfaceof a wafer W including a patterned shape such as a trench T. Thesequence in FIG. 15 is illustrated in a gas supplying order to the waferW. In other words, in the period of time t1 to t6 of the first cycle,although the showerhead part 93 supplies chlorine radicals while theseparation gas nozzles 41 and 42 supply nitrogen gas without stopping,the sequence in FIG. 15 illustrates a temporal sequence in which thegases are actually supplied to the surface of the wafer W. Morespecifically, chlorine radicals are supplied to the wafer W while thewafer W passes a location under the showerhead part 93 during the periodof time t1 to t2, and nitrogen gas is supplied while the wafer passes alocation under the separation regions D only during periods of time t2to t3 and time t4 to t5. In other words, the sequence illustrated inFIG. 15 can be applied to not only the turntable type film depositionapparatus but also a film deposition apparatus in which gases aresupplied into a process chamber containing a wafer W therein whilechanging types of the gases sequentially.

A period during time t6 to t11 corresponds to the second cycle, and aperiod during time t11 to t16 corresponds to the third cycle, any ofwhich has the same sequence as that of the first cycle. Thus, byrepeating the chlorine radical adsorption process multiple cycles, asdescribed in FIG. 14A, chlorine radicals reach the deep location of thetrench T, and the source gas can adsorb conformally.

A period during time t16 to t21 corresponds to the fourth cycle, andillustrates a sequence of consecutively performing the source gasadsorption process and the nitriding process one time after performingthe chlorine radical adsorption process one time. During time t16 tot17, the chlorine radical adsorption process is performed subsequent tothe third cycle, and the wafer W passes the first process region P1,where DCS (dichlorosilane) of the source gas during is suppled andadsorbs on the surface of the wafer W during time t18 to t19 after thewafer W passes the separation region D during time t17 to t18. At thistime, DCS adsorbs on the surface of the wafer W conformally to thesurface shape of the wafer W, thinly and uniformly as a whole. Afterpassing the location under the separation region D during time t19 tot20, the wafer W passes the location under second process region P2during time t20 to t21. In the second process region P2, the reactiongas nozzle 32 supplies an ammonia-containing gas, and ammonia plasmaionized or radicalized by the plasma generator 80 is supplied to thesurface of the wafer W. Dichlorosilane and ammonia react with each otheron the surface of the wafer W, and a molecular layer of a siliconnitride film 111 that is a reaction product is thinly deposited. Becausedichlorosilane conformally adsorbs on the surface, the molecular layerof the silicon nitride film 111 is formed conformally to the surfaceshape of the silicon nitride film 110. Moreover, because the adsorptionlayer of dichlorosilane is thin, the ammonia plasma sufficiently exertsits modification effect, and the silicon nitride film becomes ahigh-density and fine film. Thus, a high-quality and conformal siliconnitride film 111 along the surface shape of the wafer W is formed in thetrench T.

A period of time t21 to t26 corresponds to the fifth cycle, where thesame sequence as that of the first cycle is repeated. Subsequently, byrepeating the second to fourth cycles, the chlorine radical adsorptionprocess, the source gas adsorption process, and the nitriding processare sequentially repeated, thereby depositing a conformal andhigh-quality silicon nitride film on the surface of the wafer W. Then,when the film reaches a predetermined film thickness, the sequence ends.Otherwise, as necessary, further quality improvement of the siliconnitride film may be intended, by performing the plasma modificationprocess described with reference to FIG. 14D.

Thus, according to the conformal film deposition process of the methodfor depositing the silicon nitride film of the present embodiments, thehigh-quality and conformal silicon nitride film 111 to the surface shapeof the already formed silicon nitride film 110 can be deposited bywidely adsorbing chlorine radicals that become adsorption blockinggroups for the source gas containing silicon and chlorine on adsorptionradicals, causing the source gas to conformally adsorb while reducing anamount of adsorption per one time, and nitriding the source gas whilesufficiently exerting the plasma modification effect.

Moreover, although FIG. 15 illustrates the sequence of performing thesource gas adsorption process and the nitriding process one time afterperforming the chlorine radical adsorption process four times, aproportion of number of times or periods between the chlorine radicaladsorption process, the source gas adsorption process and the nitridingprocess can be set variously depending on the intended purpose.

Thus, contents of the conformal film deposition process can be setvariously. Furthermore, by combining the conformal film depositionprocess with the bottom-up film deposition process, the void and thelike can be inhibited, and the high quality filling deposition with thesilicon nitride film can be achieved.

In the method for depositing the silicon nitride film that performs thefilling deposition in two stages according to the embodiments, acombination of the bottom-up film deposition process and the conformalfilm deposition process is considered variously. For example, a cycle ofrepeating the bottom-up film deposition 5 cycles and performing theconformal film deposition 5 cycles may be alternately repeated.

Although a starting order of the bottom-up film deposition and theconformal film deposition is variously considered, for example, acombination of starting the bottom-up film deposition at first, thenalternately repeating the bottom-up film deposition and the conformalfilm deposition, and finally performing the conformal film depositionmay be adopted. Moreover, the bottom-up film deposition may be performedafter the conformal film deposition is sufficiently performed at firstto form a under coat film.

FIG. 16 is a diagram illustrating an example of a filling depositioncombining the bottom-up film deposition and the conformal filmdeposition. As illustrated in FIG. 16, a V-shaped cross section may befilled with a conformal film 111 by filling a trench T with a siliconnitride film 110 by bottom-up film deposition at first, and finallyfilling the V-shaped cross section with a conformal silicon nitride film111 by conformal film deposition.

Here, a number of repetitions of the bottom-up film deposition and theconformal film deposition can be determined variously depending on theintended purpose, and the number of repetitions can be set at a varietyof number of times as long as both of the bottom-up film deposition andthe conformal film deposition are performed at least one time.

Each of the number of repetitions may be preliminarily determined by arecipe, or may be determined by controlling timing of performing thebottom-up film deposition and the conformal film deposition depending ona film thickness using a provided film thickness measuring unit.

Furthermore, a variety of gases can be used as the source gas as long asthe gas contains silicon and chlorine. For example, as described above,in addition to dichlorosilane, a variety of chlorosilane-based gasessuch as monochlorosilane (SiH₃Cl), trichlorosilane (SiHCl₃) andhexachlorosilane (Si₂Cl₆) may be used as the source gas. Also, a varietyof nitriding gases can be used as the nitriding gas as long as thenitriding gas contain ammonia and nitrogen and can deposit a siliconnitride film as a reaction product by nitriding the source gas due tothe activation of plasma. Similarly, a variety of chlorine-containinggases can be used as long as the chlorine-containing gas can form anadsorption blocking region on a surface of a wafer W by chlorineradicals.

The sequence described in FIGS. 12 and 13 can be executed by thecontroller 100 of the above-mentioned film deposition apparatus. Thecontroller 100 controls periods of gas supply, timings, operation of theplasma generators 80 and 90, thereby performing the sequence. Becausethe film deposition apparatus according to the embodiment can rotate theturntable 2 and can change a gas supply pattern, the film depositionapparatus can control a gas supply period by controlling a number ofrevolutions while keeping the same gas supply conditions. Thus, becausethe film deposition apparatus according to the embodiment can readilyimplement the sequence in FIGS. 12 through 15 while readily controllingan adsorption amount of each gas, the method for depositing the siliconnitride film can be preferably performed.

As discussed above, according to the embodiments of the presentdisclosure, a recessed pattern can be filled with a high-quality siliconnitride film.

All examples recited herein are intended for pedagogical purposes to aidthe reader in understanding the invention and the concepts contributedby the inventor to furthering the art, and are to be construed as beingwithout limitation to such specifically recited examples and conditions,nor does the organization of such examples in the specification relateto a showing of the superiority or inferiority of the invention.Although the embodiments of the present invention have been described indetail, it should be understood that various changes, substitutions, andalterations could be made hereto without departing from the spirit andscope of the invention.

What is claimed is:
 1. A method for depositing a silicon nitride film tofill a recessed pattern formed in a surface of a substrate with asilicon nitride film, comprising steps of: depositing a first siliconnitride film in the recessed pattern formed in the surface of thesubstrate, the first silicon nitride film having a V-shaped crosssection decreasing its film thickness upward from a bottom portion ofthe recessed pattern; and depositing a second silicon nitride filmconformal to a surface shape of the first silicon nitride film, whereinthe step of depositing the first silicon nitride film comprises startingfilling the recessed pattern with the first silicon nitride film, andwherein the step of depositing the first silicon nitride film comprisessteps of: forming an adsorption blocking region on the surface of thesubstrate and a predetermined upper region of an inner surface of therecessed pattern by adsorbing chlorine radicals on the surface of thesubstrate and the predetermined upper region of the inner surface of therecessed pattern; adsorbing a source gas that contains silicon andchlorine on an adsorption site formed in a predetermined lower region inthe recessed pattern by supplying the source gas to the surface of thesubstrate including the inner surface of the recessed pattern, thepredetermined lower region being a region other than the adsorptionblocking region formed on the surface of the substrate and thepredetermined upper region of the inner surface of the recessed pattern;and depositing the first silicon nitride film on the adsorption site bysupplying a nitriding gas activated by plasma to the surface of thesubstrate including the inner surface of the recessed pattern andcausing a reaction between the source gas adsorbed on the surface of thesubstrate and the nitriding gas.
 2. The method according to claim 1,wherein the steps of depositing the first silicon nitride film anddepositing the second nitride film are alternately repeated.
 3. Themethod according to claim 1, wherein the step of depositing the secondsilicon nitride film comprises depositing the second silicon nitridefilm having a higher film density than a film density of the firstsilicon nitride film.
 4. The method according to claim 1, wherein thestep of depositing the second silicon nitride film comprises finallyfilling up the recessed pattern with the second silicon nitride film. 5.The method according to claim 1, further comprising: supplying a firstpurge gas to the surface of the substrate between the steps of formingthe adsorption blocking region and adsorbing the source gas; andsupplying a second purge gas to the surface of the substrate between thesteps of adsorbing the source gas and depositing the silicon nitridefilm.
 6. The method according to claim 5, wherein the step of depositingthe second silicon nitride film comprises: forming a second adsorptionblocking region such that a chlorine-containing gas conformally adsorbson the surface of the substrate by adsorbing second chlorine radicals onthe surface of the substrate; adsorbing a second source gas thatcontains silicon and chlorine on the second adsorption blocking regionadsorbed on the surface of the substrate; and depositing the secondsilicon nitride film on the surface of the substrate by supplying asecond nitriding gas activated by plasma to the second source gasadsorbed on the surface of the substrate.
 7. The method according toclaim 6, further comprising: supplying a third purge gas to the surfaceof the substrate between the steps of forming the second adsorptionblocking region and adsorbing the second source gas; and supplying afourth purge gas to the surface of the substrate between the steps ofadsorbing the second source gas and depositing the second siliconnitride film.
 8. The method according to claim 6, wherein the step offorming the second adsorption region is performed longer than the stepsof adsorbing the second source gas and depositing the second siliconnitride film.
 9. The method according to claim 6, wherein the steps offorming the second adsorption blocking region, adsorbing the secondsource gas and depositing the second silicon nitride film is made onecycle, and the one cycle is repeated multiple times.
 10. The methodaccording to claim 9, wherein the substrate is placed on a surface of aturntable along a circumferential direction thereof, the turntable beingprovided in a chamber, wherein a chlorine radical adsorption regioncapable of supplying the second chlorine radicals to the substrate, afirst purge region capable of supplying the third purge gas to thesubstrate, a source gas adsorption region capable of supplying thesecond source gas to the substrate, a second purge region capable ofsupplying the fourth purge gas to the substrate, and a nitriding regioncapable of supplying the activated second nitriding gas to the substrateare provided above the turntable and along the circumferential directionof the turntable, wherein the step of forming the second adsorptionblocking region is performed by rotating the turntable a firstpredetermined number of times while supplying the second chlorineradicals in the chlorine radical adsorption region, the third purge gasin the first purge region, the fourth purge gas in the second purgeregion, the second source gas in the source gas adsorption region, andthe activated second nitriding gas in the nitriding region to thesubstrate, and wherein the steps of adsorbing the second source gas anddepositing the second silicon nitride film are performed by rotating theturntable a second predetermined number of times while supplying thesecond chlorine radicals in the chlorine radical adsorption region, thethird purge gas in the first purge region, the fourth purge gas in thesecond purge region, the second source gas in the source gas adsorptionregion, the activated second nitriding gas in the nitriding region. 11.The method according to claim 10, wherein the first predetermined numberof times is greater than the second predetermined number of times. 12.The method according to claim 10, wherein the second predeterminednumber of times is one time.
 13. The method according to claim 10,wherein an area of the adsorption blocking region is adjusted by thefirst predetermined number of times.
 14. The method according to claim10, wherein the chlorine radical adsorption region, the first purgeregion, the source gas adsorption region, the second purge region, andthe nitriding region are arranged along a rotational direction of theturntable.
 15. The method according to claim 10, wherein the step offorming the second adsorption blocking region comprises supplying thesecond chlorine radicals from a showerhead.
 16. The method according toclaim 1, wherein the step of forming the adsorption blocking regioncomprises supplying the chlorine radicals generated by a remote plasmagenerator.
 17. The method according to claim 1, wherein the step offorming the adsorption blocking region comprises supplying the chlorineradicals generated by inductively coupled plasma.
 18. The methodaccording to claim 1, wherein the step of forming the adsorptionblocking region comprises supplying the chlorine radicals generated byinductively coupled plasma.
 19. The method according to claim 1, whereinthe step of adsorbing the source gas comprises adsorbing dichlorosilaneon the adsorption blocking region.